The present invention relates to a novel method and apparatus that are capable of recording flickerless stereoscopic images of high quality using a lenticular sheet and which yet have flexibility in adaptation, as required, for the performance of various image processing operations such as enlargement and reduction, as well as for alterations in the specifications of the lenticular sheet and in the number of original images to be reproduced.
A typical method of recording stereoscopic images using a lenticular sheet is shown in FIG. 13. The lenticular sheet indicated by C has a recording layer D on the back side to construct a lenticular recording material F. Original images A.sub.1 and A.sub.2 coming from different viewpoints (one from the right and the other from the left) are projected onto projection lenses B.sub.1 and B.sub.2 ; the projected original images are then separated into linear images by means of the lenticular sheet C and recorded as E.sub.1, E.sub.2, etc.
As shown in FIG. 14, the images E.sub.1 and E.sub.2 recorded on the recording layer D are viewed through the lenticular sheet C of the lenticular recording material F by means of the right and left eyes R and L. This twin-lens system provides a stereoscopic vision of the original images A.sub.1 and A.sub.2.
Conventionally, the recording of linear images on a lenticular recording material has been accomplished with a stereoscopic image recording apparatus (hereunder referred to simply as "a recording apparatus") that relies upon optical exposure (printing). With this recording apparatus, original images which are transmission images are projected from a light source such as a halogen lamp and, as shown in FIG. 13, the light transmitted through the original images passes through the projection lenses to be focused on the lenticular recording material via the lenticular sheet, whereby the original images are exposed as linear images. Japanese Patent Publication (kokoku) Nos. 5473/1967, 6488/1973, 607/1974 and 33847/1978 disclose recording apparatuses with which two original images are projected for printing on a lenticular recording material.
It is also known that stereoscopic images of high quality can be produced by increasing the number of original images. On the basis of this concept, Japanese Patent Publication (kokoku) No. 7981/1983 proposed a recording apparatus with which a number of original images are exposed sequentially on a lenticular recording material, and Japanese Patent Publication (kokoku) No. 31578/1981 proposed a recording apparatus, in which a number of original images are projected en masse onto a field lens and are then passed through projection lenses that are associated with the respective original images, whereby those original images are recorded on a lenticular recording material at the corresponding print angles.
With the aforementioned apparatus for recording stereoscopic images by an optical method, it is necessary to expose a plurality of original images by projecting them onto a lenticular recording material and, hence, the optics for projecting the original images onto the lenticular recording material will unavoidably become complex in construction and, in addition, it has only a low degree of freedom in design. Furthermore, the efforts for adaptation to changes in the recording conditions such as alterations in magnification (enlargement and reduction of the size of image to be recorded) are subject to optical or mechanical limitations.
If the viewing distance is changed, it becomes necessary to alter the specifications for the lenticular sheet, such as the pitch of lenticular lenses formed on the sheet. However, effecting such alterations is not easy since it is also necessary to make optical and mechanical alterations in the projecting conditions (system layout) such as the projecting and exposing (printing) angle. Similarly, it is also difficult to meet the requirement for changing the size of image to be recorded.
In contrast, image recording by scanning exposure requires comparatively simple optics and yet it has great flexibility in adapting to various image processing operations and to alterations in the specifications of the lenticular sheet. To take advantage of these features, various apparatus and methods have been proposed for recording image by scanning exposure.
For example, Japanese Patent Publication (kokoku) No. 3781/1984 teaches a stereoscopic image recording system in which a plurality of original images are taken with a TV camera, processed and stored in frame memories, from which the stored image signals are retrieved sequentially as (linear) images in accordance with the pitch of lenticular lenses used and, after the linear images are recorded on a recording material by scanning exposure, the lenticular sheet is bonded to the recording material.
Japanese Patent Application (kokai) NO. 295296/1989 teaches a method of preparing a stereoscopic variable pixel forming sheet, in which data for coordinates in a solid space that have been obtained from a plurality of original images carrying inherent continuous parallax information or time differential information are split into linear images that are assigned to zones corresponding to the lenticular lenses on a lenticular sheet and the formed pixels for stereoscopic image are aligned in reverse order with respect to the parallax or time differential information and recorded on a recording material,followed by bonding the lenticular sheet onto the recording material.
In the apparatus for recording stereoscopic images by scanning exposure, each original image is split into linear images on the basis of the image information carried by the plurality of original images and, after the linear images are recorded on the recording material, it must be bonded to the lenticular sheet in registry to assure that the interval of recording the linear images is in exact agreement with the pitch (P) of lenticular lenses on the lenticular sheet.
The use of a lenticular sheet in the recording of stereoscopic images has suffered from various problems such as the formation of "multiple image" (not a desired single image but two or more duplicate images are formed as offset from each other) and the flickering of the formed image. The multiple duplication of a stereoscopic image or its flickering not only tires the eyes of the viewer but also gives him great discomfort, thereby damaging the commercial value of the formed stereoscopic image.
The multiple duplication of a stereoscopic image and its flickering are caused when an unwanted linear image (of a particular original image) is viewed by the right and left eyes or when the areas where no image is recorded falls within the visual field. However, these problems have not been completely solved in the prior art of recording stereoscopic images using a lenticular sheet and, hence, there is a great need for developing a method and apparatus that are capable of reproducing stereoscopic images of a higher quality.